WASHINGTON -- A drug company hopes to win federal approval early next month for a novel cervical cancer vaccine that it touts as the next biggest thing since the pap test in fighting the No. 2 cancer in women.

Merck & Co. already has won a key endorsement of the vaccine, called Gardasil, from a Food and Drug Administration advisory committee. A final decision by the FDA is expected by June 8.

The vaccine, administered in three shots over six months at a cost of $300 to $500, protects against the two types of human papillomavirus (HPV) believed responsible for about 70 percent of cervical cancer cases.

If Gardasil ultimately wins approval, it could prove a boon to public health, though the cost could hinder its broad use.

"The vaccine community will see this as an opportunity to prevent cancer. They will also see issues of availability and cost," said Dr. Bruce Gellin, a committee member and head of the federal vaccine policy office.

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Even though Merck has played up the cancer benefits of Gardasil, it also protects against two other virus types that cause 90 percent of genital wart cases. All four virus types are sexually transmitted.

In fact, HPV is the most common sexually transmitted disease. It affects more than 50 percent of sexually active adults. The cervical cancer it can cause kills about 290,000 women worldwide each year, including 3,500 women in the United States, where regular pap smears often detect precancerous lesions and early cancer.

Merck seeks to license Gardasil in dozens of countries. The Whitehouse Station, N.J. company estimates the vaccine could slash worldwide deaths from cervical cancer by more than two-thirds.

"Gardasil has the potential to meet an unmet medical need as the first vaccine to prevent cervical cancer," Merck's Dr. Patrick Brill-Edwards told the Vaccine and Related Biological Products advisory committee. The committee endorsed the vaccine as safe and effective in five separate 13-0 votes late Thursday.

The vaccine is a "wonderful, good step" in helping eradicate cervical cancer, said Dr. Monica Farley, who heads the advisory panel. She is a bacterial infectious disease expert at the Emory University School of Medicine.

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During public comment, several speakers said the vaccine should not replace screening. Merck said the drug is not intended to do that. However, it could reduce some of the dread involved in the annual tests by eliminating many of the abnormalities they often turn up, said Dr. Eliav Barr, head of the HPV vaccine program at Merck.

The national Advisory Committee on Immunization Practices will decide late in June whether to endorse routine vaccination with the vaccine, including in what age groups.

Merck seeks approval for use of the vaccine in females age 9 to 26. The vaccine works best when given to people before they become sexually active.

That garnered some early opposition to Gardasil, out of concern that it could encourage sexual activity in the preteens and teens. But that largely faded away because of the vaccine's potential for reducing cancer.

Early vaccination remains important, since Gardasil does not necessarily protect against one or more of the four viruses in people already infected before they get the vaccine, and can increase their risk for precursors to cervical cancer. Also, Gardasil does not protect against infection from the many other virus strains not included in the vaccine.